Is Lost L. Lake safe to swim in?

Good for swimming, clear water with low algae levels. Lost L. Lake has an overall water quality grade of B. Always check local health department advisories before swimming.

Thunder Bay District County, Ontario · Water Quality Report Card

Lost L. Lake

Grade B — Good

Mesotrophic

Lost L. Lake in Thunder Bay District, Ontario received a water quality grade of B (Good). Water clarity: 1.7 m visibility. Phosphorus: 9.1 µg/L.

Clarity: 1.7 m
Type: Mesotrophic

Where to stay →Safe to swim?

Lost L. Lake is a mesotrophic lake in Thunder Bay District County, Ontario. Water quality is graded B based on 2 sampling years through 2025. Compared to the 301 other monitored lakes in Thunder Bay District County, Lost L. Lake ranks #249 for water quality.

Source: EPA Water Quality Portal sampling records, Ontario MECP, last sampled 2025-08-01. Grade methodology: LakeGrade methodology.

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Murky, only visible to about 5.6 ft. Phosphorus level: 9.1 µg/L. Trophic State Index: 44.

Metric	Value	Grade
Water Clarity (Secchi Depth)	1.7 m	D
Phosphorus	9.1 µg/L	A
Chlorophyll-a (Algae)	No data
Trophic State Index (TSI)	44	Mesotrophic

Moderate nutrients, good water quality

Where to stay near Lost L. Lake

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Fishing Lost L. Lake

→ Lost L. Lake fishing regulations (limits, seasons, special rules)

Location

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County Ranking

Ranked #249 of 302 lakes in Thunder Bay District

Cleaner Lakes Within 30 Miles

Lost L. Lake holds Grade B. 5 nearby lakes hold higher grades.

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Nearby Lakes in Thunder Bay District

Explore Lost L. Lake across LakeGrade

Lake Fishing Forecast

Species activity outlook by water temperature and season

Mesotrophic Lakes

Moderate nutrients, good water quality

The State of Ontario's Lakes

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Top 25 by overall water quality score

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Top 25 by Secchi water clarity

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Grade A/B + low algae filter

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Panfish-rich, public access

All Ontario lakes

Full state directory

Other Grade B Lakes in Ontario

Chipman Lake

Cochrane District · 3 m

Pyramid Lake

Kenora District · 2.3 m

Savoy Lake

Kenora District · 2.2 m

Mercutio Lake

Rainy River District · 2 m

Mattawa Lake

Kenora District · 2.7 m

Other Man Lake

Rainy River District · 3 m

Mesotrophic Lakes in Ontario

Chipman Lake Pyramid Lake Savoy Lake Mercutio Lake

More records, surveys & data sources

Where this data comes from

Measurements for Lost L. Lake come from the EPA Water Quality Portal. Per-sample source details are not recorded for this lake.

Data Sources

Water quality data from the EPA Water Quality Portal

Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion

Most recent sample: 2025-08-01

Monitoring stations:

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